In a tire, a large number of sipes and lateral grooves are formed in a tread portion so that the on-ice performance is secured by road surface digging frictional force (edge effect) caused by edges of the sipes and the lateral grooves (see Japanese unexamined Patent Application No. 2015-168356, for example).
In order to increase the on-ice performance, formation number and length of the sipes and the lateral grooves have been increased. However, the increase in the number and the length of the sipes and the lateral grooves causes decrease of block rigidity, therefore, it is possible that the dry steering stability and the like are deteriorated, on the other hand. As just described, there is a trade-off between the on-ice performance and the dry steering stability, and further improvement is required to have them at a high level.